1. Field of the Invention
The present invention relates to a fuel reforming apparatus for a fuel cell system.
2. Description of Related Art
As is well known, a fuel cell is a system for generating electric energy using a fuel.
In the fuel cell, a polymer electrolyte membrane fuel cell has an excellent output characteristic, a low operating temperature, and fast starting and response characteristics. Therefore, the polymer electrolyte fuel cell advantageously has a wide range of applications including a mobile power source for vehicles, a distributed power source for home or buildings, and a small-sized power source for electronic apparatuses.
The fuel cell system employing the polymer electrolyte membrane fuel cell is constructed with a fuel cell main body (hereinafter, referred to as “stack”), a fuel reformer which reforms the fuel to generate a reformed gas containing hydrogen and supplies the reformed gas to the fuel cell main body, and an oxidizing gas supply unit which supplies an oxidizing gas to the stack.
Therefore, the polymer electrolyte membrane fuel cell system generates electric energy through an electrochemical reaction between the reformed gas and oxidizing gas that are supplied to the stack.
The fuel reformer may be constructed with a heat source that generates thermal energy by direct combustion of the fuel and a reforming reaction unit that generates the reformed gas through a reforming reaction of the fuel using the thermal energy.
In the contemporary fuel reformer, a relatively high temperature combustion gas, which is generated while the fuel is burned in the heat source, is exhausted as it is. This causes the loss of the heat energy of the combustion gas and thus increased the startup time. As a result, the thermal efficiency and performance efficiency of the system are deteriorated.
In addition, since the high temperature combustion gas exhausted through an outlet of the heat source contacts locally a portion of the housing of the fuel reformer, which corresponds to the outlet of the heat source, the housing may be damaged or the thermal energy of the combustion gas may be discharged to an external space through the local portion of the housing, thereby causing the thermal insulation performance to deteriorate.
As described above, in the contemporary fuel reformer, the thermal energy generated from the heat source is discharged through the local portion of the housing and thus the startup time increases. This causes a deterioration of thermal efficiency and performance efficiency of the fuel system.